1. Field of the Invention
The invention relates to a semiconductor apparatus packaged by transfer mold method.
2. Description of the Related Art
In a conventional semiconductor apparatus packaged by transfer mold method, the size of each side of a die pad of a lead frame is designed to be not less than 0.5 mm larger than each side of a semiconductor chip to be mounted, so that when a semiconductor chip is mounted on the die pad, each edge surface of the chip is located interior to each edge side of the die pad. This is to prevent adhesive from flowing out of the die pad toward the exterior even if the adhesive protrudes to some extent when a semiconductor chip is mounted by bonding.
FIG. 1 shows a state wherein resin is molded and cured by transfer mold method for fabricating such a semiconductor apparatus. In FIG. 1, a part of the figure is omitted for ease in understanding.
In FIG. 1, 10 denotes a lead frame, 11 its die pad, 12 a semiconductor chip bonded onto the die pad 11, 13 a metallic mold for molding resin used for transfer molding, and 14 a gate of the metallic mold for injecting resin. Inside the metallic mold 13, resin for the packaging member is press-injected and cured.
As described above, according to the conventional semiconductor apparatus, bonding is achieved in such a manner that each edge surfaces of a semiconductor chip 12 is located interior to each edge side of the die pad 11. As a result, there has been a problem in that voids 15 (air bubbles) generated when resin is injected cannot escape easily and cure as they are. Especially, the voids tend to be generated easily at a position of a dead angle of the gate 14 for injecting resin, that is, on the edge surface 12a of the semiconductor chip 12 located on the opposite side of the gale 14 for injecting resin. When the resin is cured and voids 15 are formed, the reliability of the semiconductor apparatus is lowered. Particularly in an optical semiconductor apparatus such as CCD (Charge Coupled Device) or the like which is molded using transparent resin, the formation on the voids has great influence such as causing inferior appearance and the like, so that production yield decreases greatly.